But the 'carnage' at Mount Gambier Airport late yesterday afternoon was all faked, an exercise designed to test the response and collaboration of emergency services.

The realistic mid-air collision scenario, which saw a light plane set on fire and multiple deaths and casualties, certainly fooled more than one passerby, with one or two enquiring calls made to Limestone Coast police.

Others got a good vantage point from the Riddoch Highway, watching the two hour exercise play out.

Involving more than nine organisations including the SES, CFS, SA Ambulance service and the emergency department at Mount Gambier Hospital, Senior Sergeant Wendy McDonald said the mass casualty incident (MCI) exercise was a great success.

"From an emergency service perspective, it went really well," she said.

"We had the inter-agency cooperation we were looking for.

"The big thing with this is due to the number of casualties involved, we want to see the services really work together in managing the exercise but also making sure the patients were well cared for."

The exercise took more than 10 months to plan and organise.

Even the media was brought on board, with three or four 'pesky journalists' asked to test the responses from the services on site, to attempt to determine the cause of the crash.

SA Ambulance Service Operations Manager, Andrew Thomas said the exercise was an open and frank learning experience for his crew.

The service had 7 crews and a command vehicle at the site, the largest number of responders to the exercise.

After the debriefing at Mount Gambier Hospital, Mr Thomas said it was now about gaining feedback from his staff and volunteers.

"The exercise reinforced for us how long it takes to triage patients," he said.

"We will now go back and evaluate how we performed."

Mrs McDonald said the exercise was a test of protocol, but also for services to learn from the exercise, should a real event occur.